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Electrophoretic mobility for peptides with post-translational modifications in capillary electrophoresis
Jeongkwon Kim1, Robert Zand, David M Lubman
1Department of Chemistry, University of Michigan, Ann Arbor 48109-1055, USA.
Electrophoresis
|March 11, 2003
Summary
A new model, q/M(0.56), accurately predicts peptide electrophoretic mobility in capillary electrophoresis (CE) coupled with mass spectrometry (MS). This method effectively identifies post-translational modifications in complex peptide mixtures.
Area of Science:
- Analytical Chemistry
- Biochemistry
- Proteomics
Background:
- Capillary electrophoresis (CE) coupled with electrospray ionization-mass spectrometry (ESI-MS) is a powerful technique for peptide analysis.
- Accurate prediction of peptide electrophoretic mobility is crucial for effective separation and identification.
- Existing semiempirical models may not fully capture the complexities of peptide charge and molecular weight interactions.
Purpose of the Study:
- To evaluate and identify the best semiempirical model for predicting peptide electrophoretic mobility in CE-ESI-MS.
- To demonstrate the utility of the chosen model for analyzing standard peptides and post-translationally modified peptides.
- To establish a reliable method for identifying and characterizing peptide modifications.
Main Methods:
- Testing several semiempirical models for peptide electrophoretic mobility.
- Utilizing on-line CE coupled with ESI-MS for peptide separation and analysis.
- Analyzing standard peptides from myoglobin and hemoglobin digests.
- Investigating post-translationally modified peptides from human myelin basic protein digests.
Main Results:
- The expression q/M(0.56) showed the best correlation with electrophoretic mobility at pH 2.7 for 18 standard samples.
- The model accurately predicted the mobility of post-translationally modified peptides when their total charge was correctly calculated.
- Identified partial citrullination, deamidation, oxidation, phosphorylation, and methylation in human myelin basic protein peptides.
Conclusions:
- The q/M(0.56) model provides an excellent correlation for predicting peptide electrophoretic mobility in CE-ESI-MS.
- Accurate calculation of peptide charge is essential for the successful application of this model, especially for modified peptides.
- This method offers a valuable tool for identifying post-translational modifications in complex biological samples.